OVERVIEW: The purpose of this application is to support the patient-oriented research program and career development of Margaret C. Fang, MD, MPH, a fellowship-trained academic hospitalist at the University of California, San Francisco (UCSF). Dr. Fang's overall career goal is to optimize stroke prevention in older patients with atrial fibrillation. She will develop a research program that will explore clinical and biological risk factors for stroke and hemorrhage associated with atrial fibrillation, identify the optimal use of anticoagulants to prevent atrial Fibrillation-related stroke, direct attention towards social and behavioral barriers to optimal anticoagulant management, and test interventions directed at improving clinical decision-making in regards to anticoagulating the oldest patients. CAREER DEVELOPMENT PLAN: Dr. Fang will undergo formal didactic training and conduct mentored clinical research over the 5 year award period. Didactic training will include coursework and tutorials in outcomes assessment, propensity score analysis, cost-effectiveness analysis, genetic epidemiology, functional status assessment, and the sociology and biology of aging. She will obtain training in clinical geriatrics through enrolling in the UCSF Core Geriatrics Curriculum. An advisory committee of senior investigators, led by Dr. Seth Landefeld, the Chief of Geriatrics at UCSF and her Principal Mentor, will oversee all aspects of Dr. Fang's career development. RESEARCH PLAN: The aims of this researchapplication are to (1) determine how advanced age affects warfarin control and poor outcomes from warfarin;(2) assess whether functional decline, fall-risk, and cognitive impairment lead to worse outcomes on warfarin;and (3) develop and pilot test a decision tool that helps Clinicians compare the risks and benefits of prescribing warfarin for older patients with atrial fibrillation. These aims will be accomplished through 3 projects. In Project 1, Dr. Fang will analyze data from the ATRIA cohort of 13,559 people with atrial fibrillation to determine age-specific rates, risk factors, and outcomes of warfarin-associated hemorrhage and warfarin control. In Project 2, Dr. Fang will assemble a cohort of frail community-dwelling elders with atrial fibrillation to study how frailty is associated with warfarin control and outcomes. In Project 3, Dr. Fang will develop a clinical decision tool, incorporating data obtained from the first two studies, to assist clinicians decide on the optimal choice of antithrombotic therapy for older patients with atrial fibrillation. This decision tool will then be pilot tested among clinicians caring for patients with atrial fibrillation at UCSF. Together, these projects will provide practical experience and form the basis for future studies that seek to improve the safety and use of anticoagulants in the oldest patients with atrial fibrillation.